Laser Cooling to the Zero-Point Energy of Motion

Abstract

A single trapped $^{198}\mathrm{Hg}^{+}$ ion was cooled by scattering laser radiation that was tuned to the resolved lower motional sideband of the narrow $^{2}S_{\frac{1}{2}}\ensuremath{-}^{2}D_{\frac{5}{2}}$ transition. The different absorption strengths on the upper and lower sidebands after cooling indicated that the ion was in the ground state of its confining well approximately 95% of the time.